This application is a National Stage application that claims the priority of PCT/NL97/00678 filed Dec. 9, 1997 and Netherlands application No. 1004824 filed Dec. 18, 1996.
The invention relates to a method for separating metals and/or metal alloys of different melting points, a mixture of the said metals and/or metal alloys being brought to a temperature at which the metal or the metal alloy of relatively low melting point is molten and the metal or the metal alloy of relatively high melting point is in the solid state, and finally separating the solid constituents from the melt.
The suspension of solid constituents in a melt can be made, on the one hand, by heating a solid substance so that only the low-melting components melt and, on the other hand, by cooling a melt so that a fraction of the melt crystallizes out.
In practice, aluminium is produced using an electrolysis process which uses considerable amounts of energy. Also known is a process as indicated in the introduction in which metals, including aluminium, are refined by fractional crystallization from the melt (cf. journal "Metall" No. 7-8/95, pp. 491-495). In this process, the crystals and the melt are separated inefficiently, for example by pressing the crystals downwards using a compression means to form a compact mass.